Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221334 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 934 AM EDT WED APR 22 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE FORECAST AREA THIS AFTERNOON WITH A WEAKER COLD FRONT FOLLOWING ON THURSDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO CUT ACROSS THE TENNESSEE VALLEY AND THE CAROLINAS SATURDAY INTO SATURDAY NIGHT. A HIGH PRESSURE SYSTEM WILL GRADUALLY BUILD IN FROM THE WEST ON SUNDAY AND REACH THE APPALACHIANS BEFORE WEAKENING ON MONDAY. A STRONG LOW PRESSURE SYSTEM IS PREDICTED TO START ORGANIZING IN THE CENTRAL UNITED STATES ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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930 AM UPDATE...NO MAJOR CHANGES WITH THE FORECAST. COLD FRONT IS SLOWLY TRUDGING THROUGH CENTRAL PA AT THIS TIME. SHOWERS HAVE BECOME WIDESPREAD AND THERE HAVE BEEN A FEW LIGHTNING STRIKES OVER SOUTHWESTERN PA AND NORTHERN WV. PREVIOUS NEAR TERM DISCUSSION...AN AREA OF LOW PRESSURE WILL SLOWLY PINWHEEL AROUND IN SOUTHEAST CANADA THROUGH TODAY, BRINGING A COLD FRONT ACROSS THE AREA LATER THIS AFTERNOON. MOSTLY SUNNY/PARTLY CLOUDY SKIES WILL BEGIN TO DAY TODAY, BUT CLOUD COVER WILL BE ON THE INCREASE AHEAD OF AN APPROACHING COLD FRONT. THERE ARE SOME SCATTERED SHOWERS TO OUR WEST EARLY THIS MORNING AS THERE IS SOME WEAK VORTICITY IMPULSES SLIDING THROUGH PENNSYLVANIA. THESE SCATTERED SHOWERS WILL CONTINUE THROUGH THE MORNING, BUT MORE WIDESPREAD ACTIVITY IS EXPECTED TO DEVELOP TO OUR WEST LATER THIS MORNING INTO THIS AFTERNOON ALONG AND AHEAD OF THE APPROACHING COLD FRONT. INSTABILITY IS FORECAST TO INCREASE ACROSS THE AREA DURING THE DAY WITH CAPE VALUES AROUND 200-300 J/KG AND SLIGHTLY NEGATIVE LI`S, SO THERE COULD BE SOME THUNDERSTORMS DEVELOP AS THE LINE OF SHOWERS MOVES EASTWARD. IF ANY THUNDERSTORMS DO DEVELOP, THEY COULD PRODUCE STRONG GUSTY WINDS, OR EVEN SMALL HAIL WITH THE FREEZING LEVEL BEING PRETTY LOW. AS WE BEGIN TO WARM THIS MORNING AFTER THE SUN COMES UP, STRONG MIXING WILL BEGIN TO TAKE PLACE ACROSS THE AREA. THIS WILL ALLOW WINDS ABOVE THE SURFACE TO BEGIN TO MIX DOWN TO THE SURFACE. GUSTY WINDS ARE EXPECTED TODAY, WITH THE STRONGEST WINDS EXPECTED DURING THE AFTERNOON, REACHING 30-40 MPH. THERE IS THE POSSIBILITY THAT EVEN STRONGER WINDS COULD OCCUR WITH THE SHOWERS/THUNDERSTORMS THIS AFTERNOON AS THEY COULD CARRY STRONGER WINDS DOWN TO THE SURFACE.
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&& .SHORT TERM /THURSDAY/... THE COLD FRONT AND ASSOCIATED SHOWERS/THUNDERSTORMS ARE EXPECTED TO BE MAKING THEIR WAY ACROSS THE AREA DURING THE EARLY EVENING HOURS. THERE COULD REMAIN SOME ISOLATED/SCATTERED SHOWERS BEHIND THE FRONT INTO THE LATE EVENING HOURS AS THE COLD POOL ALOFT MOVES ACROSS THE AREA. WE EXPECT ANY SHOWER ACTIVITY TO BE ENDING AROUND OR SHORTLY AFTER MIDNIGHT AS THE SHORT WAVE MOVES PAST THE AREA. SOME PARTIAL CLEARING MAY BEGIN TAKING PLACE OVERNIGHT, BUT WE DON`T EXPECT ALL CLEAR SKIES. TEMPERATURES OVERNIGHT WILL COOL BEHIND THE COLD FRONT. IT IS POSSIBLE FOR SOME PATCHY FROST TO DEVELOP ACROSS PORTIONS OF NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY, BUT SINCE IT IS NOT EXPECTED TO BE WIDESPREAD SINCE THERE COULD REMAIN A STEADY BREEZE INTO THE NIGHT, WE HAVE KEPT IT OUT OF THE FORECAST FOR NOW. THE POCONOS WILL BE THE COLDEST AND MOST LIKELY AREA FOR FROST, BUT SINCE THE GROWING SEASON HAS NOT STARTED THERE YET, WE DID NOT ISSUED AN ADVISORY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... NO CHANGE TO THE BLOCKY / -NAO PATTERN IN THE LONG TERM. NOT MUCH PRECIPITATION IS EXPECTED TO OCCUR THROUGH TUESDAY WITH THE MAIN IMPACT BEING BLUSTERY AND POSSIBLY FROSTY CONDITIONS AT THE START OF THE LONG TERM, WITH A SLIGHT EASING/RECOVERY TOWARD THE LATTER HALF. BEYOND OUR DETERMINISTIC FORECASTS, THE CAN GGEM AND ECMWF ARE PREDICTING A RATHER STRONG NOR`EASTER. WHILE THE FIRST NEEDED INGREDIENT (NEGATIVE NAO) IS IN PLACE, ITS PREDICATED ON IT RELAXING (THE ARCHAMBAULT EFFECT) AS THE SURFACE LOW MAKES THE TURN ALONG THE COAST. CONTRAST THAT SOLUTION WITH THE SATURDAY SYSTEM IN WHICH THE TELECONNECTION IS STILL PREDICTED NEGATIVE. THAT LOW IS EXPECTED TO EXIT STAGE SOUTH. MANY SOUNDING RUNS TO GO WITH THE FORMER AND FOR NOW WE WILL TAKE ONE LOW AT A TIME. BOTH THE GFS AND WRF-NMM INITIALIZED THE CLOSED LOW WELL AT 500MB. WHILE NEAR STREAM LOCALES WERE SOMETIMES 1C WARMER THAN INITIALIZED, THE CORE OF THE CHILLY AIR ENTERING MINNESOTA WAS COLDER THAN INITIALIZED. SPEAKING OF COLDER, A REINFORCING COLD FRONT IS EXPECTED TO MOVE THROUGH OUR CWA ON THURSDAY. WITH THE HIGH PRESSURE SYSTEM STILL REMOVED FROM OUR AREA, THE SUBSIDENCE INVERSION IS WELL ABOVE THE SURFACE. LOOKS LIKE MORE SELF DESTRUCT SUNSHINE THAN WE THOUGHT YESTERDAY. ALSO WITH THE INVERSION WELL DISPLACED FROM THE SURFACE, CLOUDS SHOULD GET SOME VERTICAL DEVELOPMENT. WHILE WE ARE EXPECTED TO BE BETWEEN STRONG SHORT WAVES, THE DEEPER MOISTURE NORTH COULD SUPPORT SOME SHOWERS. IF THEY DEVELOP FAST ENOUGH ON THURSDAY MORNING, SNOW SHOWERS MIGHT OCCUR OVER THE HIGHER TERRAIN. MAX TEMPS WILL BE LOWER THAN TODAY AS WE WILL BE GETTING DEEPER INTO THE CHILLY AIR MASS. STAT GUIDANCE LOOKS REASONABLE BASED ON PREDICTED 925MB AND 2M TEMPS. LASTLY IT WILL BE WINDY AGAIN, BUT WE SHOULD NOT HAVE AS MANY SHOWERS OR HAVE WIDESPREAD EVAPORATIONAL COOLING ENHANCEMENT TO THE WINDS. ON THURSDAY NIGHT, WE MIGHT NEED FROST OR FREEZE RELATED HEADLINES IN PA AND NJ WHERE THE GROWING SEASON HAS STARTED. AS OF TODAY THIS INCLUDES ALL OF OUR NORTHERN CWA EXCEPT FOR THE POCONOS. THIS LOOKS MORE ADVECTIVE THAN RADIATIONAL WHICH MAKES THIS AIR MASS EVEN MORE IMPRESSIVE. ANOTHER CHILLY DAY ON FRIDAY, BUT HERE THE NAM/WRF IS NOT AS AGGRESSIVE WITH CONVECTIVE TEMPS BEING REACHED AND EVEN THE GFS HAS LESS PREDICTED MOISTURE. WE WOULD EXPECT A BROKEN DECK OF CLOUDS TO STILL FORM BY AFTERNOON, ESPECIALLY THE NORTHERN HALF OF OUR CWA. MAX TEMPS SHOULD BE SIMILAR TO THURSDAY`S WITH SLIGHTLY WEAKER WINDS. WINDS SHOULD FINALLY START DECREASING ON FRIDAY NIGHT AS THE HIGH PRESSURE SYSTEM NEARS. THAT IS THE GOOD NEWS. THE BAD NEWS IS WITH A CHILLY AIR MASS IN PLACE THIS MAKES A RADIATIONAL COOLING NIGHT WITH MORE FROSTY CONDITIONS POSSIBLE, ESPECIALLY IN MORE RURAL LOCATIONS. WITH THE SOUTHERN SLIDER SYSTEM ON SATURDAY AND SATURDAY NIGHT, THE GFS (GOING NORTH) AND ECMWF (NOW AMONG THE MOST SOUTHWARD SUPPRESSED) HAVE FLIPPED THEIR POSITIONS. THE COMMON THREAD THEY ARE VACILLATING OVER IS OUR CWA BEING NEAR THE NORTHERN FRINGE OF PCPN CHANCES. WE KEPT THE LOW CHANCE SOUTH SATURDAY AFTERNOON (SLOWER TIMING) INTO SATURDAY NIGHT. CLOUDS WOULD KEEP SATURDAY MAX TEMPS FROM REBOUNDING FURTHER. ON THE FLIP SIDE CLOUDS SHOULD KEEP SATURDAY NIGHT`S MIN TEMPS HIGHER. A WEAKENING HIGH PRESSURE SYSTEM IS THEN EXPECTED TO TRY TO REACH OUR CWA SUNDAY INTO MONDAY. TEMPERATURES SHOULD RETURN CLOSER TO NORMAL LEVELS WITH OVERALL DRY WEATHER MAINTAINED. BECAUSE OF TIMING AND INTENSITY ISSUES, WE PUT IN A LOW CHANCE FOR RAIN ON TUESDAY. ALBEIT A GREATER, NASTIER CHANCE MIGHT POSSIBLY OCCUR LATER IN THE WEEK. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS ARE EXPECTED FOR MOST OF THE TAF PERIOD. CLOUDS WILL INCREASE AND LOWER THROUGH THE DAY AHEAD OF AN APPROACHING COLD FRONT...HOWEVER CEILINGS SHOULD REMAIN VFR. WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS WILL ACCOMPANY THE FRONT. THEREFORE, A BRIEF PERIOD (GENERALLY A 2 TO 3 HOUR WINDOW) OF MVFR VISIBILITIES ARE POSSIBLE WITH THESE SHOWERS AND STORMS. AT THIS TIME, THINK KRDG AND KABE SHOULD SEE PRIMARILY SHOWERS AS INSTABILITY IS LIMITED FURTHER WEST. FOR THE REST OF THE TAF SITES, INCLUDING KPHL, KTTN, KPNE, KILG, KMIV, AND KACY, THERE IS A HIGH ENOUGH RISK OF TSRA TO INCLUDE THAT MENTION IN THE TAFS. WINDS WILL INCREASE LATER THIS MORNING OUT OF THE SOUTHWEST, AND COULD GUST AROUND 30-35 KNOTS BY THIS AFTERNOON. STRONGER WINDS COULD OCCUR IF THUNDERSTORMS OCCUR AS WELL. THE STRONG WIND GUSTS WILL BEGIN TO WEAKEN LATE IN THE AFTERNOON INTO THE EVENING, BEFORE GUSTS DROP OFF OVERNIGHT, ALTHOUGH A STEADY BREEZE SHOULD REMAIN ACROSS THE AREA. OUTLOOK... THURSDAY AND THURSDAY NIGHT...VFR CONDITIONS EXPECTED. WESTERLY WINDS WILL BECOME GUSTY IN THE MORNING, GUSTS 20 TO 25 KNOTS, THROUGH THE AFTERNOON BEFORE DIMINISHING IN THE EVENING AND NIGHT. FRIDAY AND FRIDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED. WESTERLY WINDS WILL BECOME GUSTY IN THE MORNING, GUSTS UP TO 20 KNOTS, THROUGH THE AFTERNOON BEFORE DIMINISHING IN THE EVENING. SATURDAY AND SATURDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED. SOME SHOWERS POSSIBLE FROM KPHL AND TO THE SOUTH AND EAST. SUNDAY...MAINLY VFR CONDITIONS EXPECTED.
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&& .MARINE... SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL OF THE WATERS TODAY. WINDS ARE EXPECTED TO BEGIN GUSTING 25-30 KNOTS LATER THIS MORNING INTO THE AFTERNOON AND SEAS ON THE OCEAN WILL BUILD AGAIN TO 5-6 FEET. THERE IS SOME 35-40 KNOT WINDS ABOVE THE SURFACE, BUT WITH THE COOL WATERS, THE INVERSION IS EXPECTED TO PREVENT THESE STRONG WINDS FROM MIXING DOWN TO THE SURFACE. OUTLOOK... THURSDAY THROUGH FRIDAY...GUSTY WESTERLY WINDS THURSDAY AND FRIDAY THAT COULD REACH SMALL CRAFT ADVISORY LEVELS. THE PRESENT SMALL CRAFT ADVISORY APPEARS DESTINED FOR AN EXTENSION INTO THIS TIME PERIOD. FRIDAY NIGHT THROUGH SUNDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED ON THE AREA WATERS. SOME RESIDUAL SMALL CRAFT ADVISORY CONDITIONS MIGHT OCCUR ON FRIDAY EVENING ON THE OCEAN. && .RIP CURRENTS... OUR SURF ZONE FORECASTS START FRIDAY THE 15TH OF MAY AND A PNS WAS ISSUED AROUND 554 PM ANNOUNCING THE NEW BEACH HAZARDS STATEMENT THAT WILL SUPPLEMENT OUR PRIMARY RIP CURRENT RISK PRODUCTS. WMO HEADER WHUS41 KPHI AWIPS ID CFWPHI THATS THE HEADER THE PUBLIC INFORMATION STATEMENT EXPLAINS IT ALL. WE WILL BE ISSUING THE BEACH HAZARDOUS STATEMENT ON AN AS NEEDED BASIS TO SUPPORT SURF ZONE SAFETY, BUT NO REDUNDANCY WITH OTHER PRODUCTS. EMPHASIS FOR OUR OFFICE MAY BE ECOLOGICAL (RED TIDE) OR WIDESPREAD AND ANOMALOUSLY COLDER THAN NORMAL WATERS, POSSIBLY A RARE SQUALL LINE PRESSURE INDUCED SEICHE. THIS BEACH HAZARD STATEMENT WILL BE EVOLVING OVER THE COMING YEARS AND WILL CONTAIN INFORMATION THAT CANNOT BE FOUND IN ANY OTHER MOUNT HOLLY NON-AFD PRODUCT. IT WILL NOT REPLACE THE PRIMARY METHOD OF INFORMING ABOUT DANGEROUS RIP CURRENTS, AT LEAST NOT FOR THIS YEAR. STATEMENTS FROM THIS PROGRAM COULD BEGIN AS EARLY AS THE START OF OUR MOUNT HOLLY SURF ZONE FORECAST PROGRAM, FRIDAY MAY 15TH BUT LIKELY BE DELAYED. THE RECENT COASTAL RESILIENCY WORKSHOP IN VIRGINIA WAS INFORMATIVE AND CHANGES ARE COMING THE NEXT SEVERAL SEASONS BEYOND 2015. HOPEFULLY THESE CHANGES FURTHER IMPROVE AWARENESS OF THE RIP CURRENT DANGER. THE OCEAN IS NOT YOUR CALM SWIMMING POOL. EVENTUALLY PROBABILISTIC TIME OF DAY INFORMATION REGARDING RIP CURRENT RISK WILL BE DEVELOPED AND VALIDATED BY OBSERVATION. THIS WILL TAKE INTO ACCOUNT BEACH BATHYMETRY, EVEN AS IT IS CONSTANTLY ADJUSTING, AS WELL AS TIDAL RELATED TOTAL WATER LEVEL. THERE WILL NO LONGER BE ANY ASSOCIATION OF RIP CURRENT RISK AND SWIMMER SKILL. TOO MANY PEOPLE ARE BECOMING VICTIM TO RIP CURRENTS NO MATTER WHAT SWIMMING SKILL LEVEL, IN LARGE PART DUE TO SWIMMING AT UNGUARDED BEACHES. RIP CURRENT AWARENESS WEEK IS JUNE 7-13. MORE TO RIP CURRENT INFORMATION TO COME HERE AND IN POSSIBLE PUBLIC FORUMS. REMAINING CALM AND FLOATING IS EXTREMELY IMPORTANT WHEN BEING SWEPT SEAWARD...THEN ITS AN ATTEMPT TO SWIM OUT OF THESE NARROW SWIFT CURRENTS OF WATER...PARALLEL TO THE SHORE. RESEARCH IS DEMONSTRATING THAT MOST OF THESE CURRENTS EVENTUALLY CIRCLE BACK TOWARD THE SHORE. SST`S DESPITE THE NEAR RECORD COLD WATERS OF FEBRUARY 20-MARCH 1 HAVE RECOVERED TO NEAR NORMAL AND ACTUALLY ARE WELL ABOVE NORMAL NOT TOO FAR OFFSHORE, AROUND LONGITUDE 73W. WE ATTM HAVE NOTHING NEW TO REPORT ON SURF ZONE WAVE RELATED INJURY RESEARCH BEING CONDUCTED IN DELAWARE. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ430-431- 450>455. && $$ SYNOPSIS...GIGI/MEOLA NEAR TERM...JOHNSON/ROBERTSON SHORT TERM...ROBERTSON LONG TERM...GIGI AVIATION...GIGI/JOHNSON/ROBERTSON/MEOLA MARINE...GIGI/ROBERTSON/MEOLA RIP CURRENTS...DRAG

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